Quote Originally Posted by goBoating View Post
I must disagree. Back to high school physics class. There are two types of friction static and dynamic. Static friction exists between two surfaces that are not moving relative to each other (tires gripping pavement and not spinning). Dynamic friction exists between two surfaces that are moving relative to each other (spinning tires on stationary pavement). For nearly every pair of materials known (one material on each side .... rubber and asphalt), the coefficient of dynamic friction is lower than the coefficient of static friction. People look at that and assume that you are stressing your drive train less if you spin your tires.

Well, in order to break the tires loose you must break the static friction. The absolute maximum stress happens just before your tires break loose... where static friction is at it's maximum. So, to get into a dynamic friction situation you have to push the drive train through the highest possible stress = max static friction. This has to be harder on the drive train than staying below that max static friction.

I've asked Subaru about this specifically. They sent me a well written email about how it is better to slip the clutch more than trying to get the tires spinning. They pointed out that the clutch is a wear item where the gears are not. One is much cheaper to replace than the other.

just my $0.02

Though this thread is almost 2 and a half years old...this is one of the best posts I've seen recently. The information and descriptions here are very clear cut and paint a great picture. Kudos my friend

I will have to agree from experience, that slipping the clutch is safer and yields better results. I have run my best times in the quarter by slipping on the launch as opposed to dumping. Dumping is just scary and even sounds horrible...so imagine what your gears are saying to you in Gear language when you just dump the clutch?

What the above poster means (at least what I believe he is trying to get across), is that moment of static friction is in the transmission, when the gears are clenched against each other for that millisecond, is when the force is tremendous and has the most potential to start cracking gears: Hence broken trannies in 1st gear on WRXs.